S.D.

I don't think you can. I also know that the rifle shot is air unblockable, even if it's not charged. so even if your timing is a bit off you have that as a back up plan.

Uh, Akihiko players use it, it's kinda important since S-Hold Killrush is invulnerable, unlike the normal one so it's a good way to get in and punish blockstrings that aren't tight.